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This paper presents joint 3D MT, gravity, and MEQ tomography inversions at the Darajat geothermal filed, in Java, Indonesia, using cross-gradients to link the different geophysical properties. An additional structural constraint is provided via cross-gradients to the current geological porosity model for the field. The intention is to include this manuscript in the First Break special edition "Energy, Technology, Sustainability” in June 2018.

The Atlantis Field has gone through more than two decades of continuous seismic imaging efforts, during which time many innovative technologies were incubated, the most recent one being the successful application of full-waveform inversion (FWI) in salt environments. This technique led to a significant improvement in the subsalt image. However, imaging challenges remain for the Atlantis reservoirs, primarily due to the complex overburden salt geometries and the highly compartmentalized reservoir. Even with an improved velocity model from FWI, the conventional reverse time migration (RTM) images still suffer from illumination issues and contain strong migration swings that hinder the subsalt imaging and subsequent interpretations. Furthermore, early versions of FWI employed an acoustic assumption, leading to visible salt halos at the salt boundaries in the velocity model, which adversely impacted the reservoir imaging. In the last 12 months, elastic time-lag FWI (TLFWI) and FWI-derived reflectivity (FDR) imaging using long-offset ocean-bottom node data have minimized these imaging issues at Atlantis, providing another step change in subsalt understanding. Although the 3D RTM images using the elastic FWI velocity model are similar overall to their acoustic counterparts, the 4D time-lapse RTM images at Atlantis show noticeable improvements. Furthermore, FDR images derived from elastic FWI velocities show obvious benefits over the acoustic ones. With a more accurate modeling engine that allows for better match between synthetic and real data, FDR imaging shows improved illumination, higher signal-to-noise ratio, and better reservoir details over acoustic FDR imaging. This recent advancement in using elastic TLFWI has had immediate positive effects in facilitating the Atlantis Field’s current and future development.

The Gulf of Mexico (GoM) is one of the most prolific oil and gas producing provinces in the world. The Mad Dog Field, like many large deepwater fields in the GoM, is subsalt. The geometric complexity of the overlying salt causes extremely variable image quality of the strata beneath the salt. Improving the seismic image has been critical for field development, and a tremendous amount of effort has been expended over the years to solve this problem. Over the past two decades, data acquisition has evolved from narrow-azimuth towed streamer to wide-azimuth streamer, and finally to ocean-bottom nodes. Processing methods such as using different anisotropic velocity models of increasing complexity, exhaustive iterations of salt modeling, acoustic full-waveform inversion, and most recently elastic full-waveform inversion have been applied. Dozens of wells have been drilled at Mad Dog guided by the resulting seismic images, and many acquisition and processing learnings have been acquired and implemented over this period to optimize the imaging. This paper explores the techniques that have caused major uplift to subsalt imaging and some techniques that were of only minor impact, while giving a glimpse into the imaging history of one of the GoM’s giant fields.

Sercel has launched MetaBlue, a ground-breaking data-driven solution for marine seismic survey planning and management.

CGG announced today that Sercel now has a complete portfolio of seabed nodal solutions for all water depths down to 6,000 m to meet growing industry demand for ocean bottom node (OBN) seismic surveys.

CGG announced today that Sercel now has a complete portfolio of seabed nodal solutions for all water depths down to 6,000 m to meet growing industry demand for ocean bottom node (OBN) seismic surveys.